Method and apparatus for flexibly regulating internal combustion engine valve flow

Abstract

In an internal combustion engine, a fixed engine valve timing profile may be combined with a variable profile produced by a valve actuator coupled to one or more engine valves. By controlling one or more engine valves independent of the fixed timing profile, engine gas flow may be more flexibly regulated, thereby optimizing engine performance under a wide variety of operating conditions. In one embodiment, enhanced internal exhaust gas recirculation (EGR) may be achieved. A turbocharger may be used, along with the control provided by the valve actuator, to further control engine gas flow. In this manner, the present invention facilitates greater control of engine gas flow with minimal cost and complexity.

What is claimed is:  
     
       1. A method comprising the steps of: 
       operatively coupling a valve actuator to at least one intake valve of an internal combustion engine, wherein the at least one intake valve is controlled in part by operation of a fixed timing mechanism;  
       controlling operation of the at least one intake valve via the valve actuator independent of position of the fixed timing mechanism to regulate engine gas flow;  
       wherein the controlling step is provided independently for each cylinder of the internal combustion engine.  
     
     
       2. The method of  claim 1 , wherein the valve actuator is controllable to effectuate variable levels of internal exhaust gas recirculation in the internal combustion engine. 
     
     
       3. An improved internal combustion engine of the type having at least one combustion chamber coupled to at least two valves, the at least two valves comprising at least one intake valve and at least one exhaust valve, wherein operation of the at least two valves is controlled in part by operation of a fixed timing mechanism, the improvement comprising: 
       a valve actuator, operatively coupled to at least the at least one intake valve of the at least two valves, for controlling operation of the at least one valve independent of position of the fixed timing mechanism,  
       wherein the valve actuator is controllable to regulate engine gas flow.  
     
     
       4. The improved internal combustion engine of  claim 3 , further comprising digital control means, coupled to the valve actuator, for controlling operation of the valve actuator. 
     
     
       5. The improved internal combustion engine of  claim 3 , wherein the valve actuator further comprises a limiter for limiting a range of operation of the at least one valve. 
     
     
       6. A diesel engine comprising the improved internal combustion engine of  claim 3 . 
     
     
       7. The improved internal combustion engine of  claim 3 , wherein the valve actuator is controllable to effectuate variable levels of internal exhaust gas recirculation. 
     
     
       8. The improved internal combustion engine of  claim 3 , wherein the at least two valves are each controllable independent of position of the fixed timing mechanism, such that each of the at least two valves is capable of opening at any position of the fixed timing mechanism and such that each of the at least two valves is capable of closing at any position of the fixed timing mechanism. 
     
     
       9. The improved internal combustion engine of  claim 3 , wherein the valve actuator comprises a pressure-actuated piston, the improved internal combustion engine further comprising: 
       a source of pressurized hydraulic fluid; and  
       a fluid control valve operatively coupled between the source of pressurized hydraulic fluid and the pressure-actuated piston,  
       wherein operation of the fluid control valve regulates application of the pressurized hydraulic fluid to the pressure-actuated piston to control operation of the pressure-actuated piston.  
     
     
       10. The improved internal combustion engine of  claim 3 , further comprising digital control means, coupled to the fluid control valve, for controlling operation of the fluid control valve. 
     
     
       11. An internal combustion engine comprising: 
       at least one combustion chamber;  
       at least two valves coupled to the combustion chamber, the at least two valves comprising at least one intake valve and at least one exhaust valve, wherein operation of the at least two valves is controlled in part by operation of a fixed timing mechanism and independent of operation of other valves for each combustion chamber other than the at least one combustion chamber;  
       a valve actuator, operatively coupled to at least one valve of the at least two valves, for controlling operation of the at least one valve independent of position of the fixed timing mechanism;  
       a turbocharger comprising:  
       a turbine coupled to a compressor;  
       an input port operatively positioned to receive exhaust gases from the combustion chamber via the at least one exhaust valve to thereby drive the turbine and the compressor; and  
       an output port operatively positioned to provide pressurized air received from the compressor to the combustion chamber via the at least one intake valve, wherein the valve actuator and turbocharger are controllable to regulate engine gas flow.  
     
     
       12. The internal combustion engine of  claim 11 , wherein the turbocharger comprises a variable nozzle turbocharger. 
     
     
       13. The improved internal combustion engine of  claim 11 , wherein the valve actuator further comprises a limiter for limiting a range of operation of the at least one valve. 
     
     
       14. A diesel engine comprising the internal combustion engine of  claim 11 . 
     
     
       15. The internal combustion engine of  claim 11 , wherein the valve actuator and turbocharger are controllable to effectuate variable levels of internal exhaust gas recirculation. 
     
     
       16. The internal combustion engine of  claim 11 , wherein the at least two valves are each controllable independent of position of the fixed timing mechanism, such that each of the at least two valves is capable of opening at any position of the fixed timing mechanism and such that each of the at least two valves is capable of closing at any position of the fixed timing mechanism. 
     
     
       17. In an internal combustion engine having at least one combustion chamber coupled to at least two valves, the at least two valves comprising at least one intake valve and at least one exhaust valve, wherein operation of the at least two valves is controlled in part by operation of a fixed timing mechanism, a method for effectuating internal exhaust gas recirculation, the method comprising: 
       operatively coupling a valve actuator to at least one valve of the at least two valves;  
       controlling operation of the at least one valve via the valve actuator independent of position of the fixed timing mechanism and independent of engine operating condition to regulate engine gas flow.  
     
     
       18. The method of  claim 17 , wherein the valve actuator is coupled to the at least one intake valve, and wherein controlling operation of the at least one valve further comprises advancing opening of the at least one intake valve. 
     
     
       19. The method of  claim 17 , wherein the valve actuator is coupled to the at least ne intake valve, and wherein controlling operation of the at least one valve further comprises retarding closing of the at least one intake valve. 
     
     
       20. The method of  claim 17 , wherein the valve actuator is coupled to the at least one exhaust valve, and wherein controlling operation of the at least one valve further comprises advancing opening of the at least one exhaust valve. 
     
     
       21. The method of  claim 17 , wherein the valve actuator is coupled to the at least one exhaust valve, and wherein controlling operation of the at least one valve further comprises retarding closing of the it least one exhaust valve. 
     
     
       22. The method of  claim 17 , wherein the valve actuator further comprises a pressure-actuated piston, the method further comprising: 
       operatively coupling a source of pressurized hydraulic fluid to the pressure-actuated piston; and  
       regulating application of the pressurized hydraulic fluid to the pressure-actuated piston to control operation of the pressure-actuated piston.  
     
     
       23. The method of  claim 17 , wherein controlling operation of the at least one valve further comprises controlling operation of the at least one valve to effectuate variable levels of internal exhaust gas recirculation. 
     
     
       24. The method of  claim 17 , wherein the at least two valves are each controllable independent of position of the fixed timing mechanism, such that each of the at least two valves is capable of opening at any position of the fixed timing mechanism and such that each of the at least two valves is capable of closing at any position of the fixed timing mechanism. 
     
     
       25. In an internal combustion engine having at least one combustion chamber coupled to at least two valves, the at least two valves comprising at least one intake valve and at least one exhaust valve, wherein operation of the at least two valves is controlled in part by operation of a fixed timing mechanism, and wherein a turbocharger is operatively positioned to receive exhaust gases from the combustion chamber via the at least one exhaust valve and to provide pressurized air to the combustion chamber via the at least one intake valve, a method for effectuating internal exhaust gas recirculation, the method comprising: 
       operatively coupling a valve actuator to at least one valve of the at least two valves;  
       controlling operation of the at least one valve via the valve actuator independent of position of the fixed timing mechanism to effectuate Internal exhaust gas recirculation; and  
       controlling operation of the turbocharger to regulate engine gas flow by at least controlling operation of the turbocharger to effectuate variable levels of internal exhaust gas recirculation.  
     
     
       26. The method of  claim 25 , wherein the valve actuator is coupled to the at least one intake valve, and wherein controlling operation of the at least one valve further comprises advancing opening of the at least one intake valve. 
     
     
       27. The method of  claim 25 , wherein the valve actuator is coupled to the at least one intake valve, and wherein controlling operation of the at least one valve further comprises retarding closing of the at least one intake valve. 
     
     
       28. The method of  claim 25 , wherein the valve actuator is coupled to the at least one exhaust valve, and wherein controlling operation of the at least one valve further comprises advancing opening of the at least one exhaust valve. 
     
     
       29. The method of  claim 25 , wherein the valve actuator is coupled to the at least one exhaust valve, and wherein controlling operation of the at least one valve further comprises retarding closing of the at least one exhaust valve. 
     
     
       30. The method of  claim 25 , wherein controlling operation of the turbocharger further comprises adjusting nozzle vane closure of the turbocharger. 
     
     
       31. The method of  claim 25 , wherein the at least two valves are each controllable independent of position of the fixed timing mechanism, such that each of the at least two valves is capable of opening at any position of the fixed timing mechanism and such that each of the at least two valves is capable of closing at any position of the fixed timing mechanism.